GHSA-x77j-w7wf-fjmw
MEDIUMGHSA-x77j-w7wf-fjmw is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in nunjucks. O3 Security confirms whether GHSA-x77j-w7wf-fjmw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Nunjucks autoescape bypass leads to cross site scripting
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
nunjucksnpmDescription
Impact
In Nunjucks versions prior to version 3.2.4, it was possible to bypass the restrictions which are provided by the autoescape functionality. If there are two user-controlled parameters on the same line used in the views, it was possible to inject cross site scripting payloads using the backslash \ character.
Example
If the user-controlled parameters were used in the views similar to the following:
<script>
let testObject = { lang: '{{ lang }}', place: '{{ place }}' };
</script>
It is possible to inject XSS payload using the below parameters:
https://<application-url>/?lang=jp\&place=};alert(document.domain)//
Patches
The issue was patched in version 3.2.4.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | nunjucks | all versions | 3.2.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nunjucks. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update nunjucks to 3.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x77j-w7wf-fjmw is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-x77j-w7wf-fjmw is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-x77j-w7wf-fjmw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-x77j-w7wf-fjmw in your dependencies?
O3 detects GHSA-x77j-w7wf-fjmw across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.